1. Field of the Invention
The present invention relates to RFID threads, which are attached to or rolled in securities, banknotes and the like to prevent forgery thereof, and sheet-shaped materials using them. In particular, the invention relates to semiconductor chip-incorporated ones which allow at least contactless retrieval of information.
2. Description of the Related Art
Conventionally, to provide a thin sheet of paper or the like with an RFID, it is common to affix the RFID to a seal-like tag coated beforehand with gum or the like and then affix this seal to the objective thin sheet.
In other known methods, an RFID tag formed beforehand into a thread shape is rolled in paper (Patent Document 1) and an RFID tag is fixed with gum between two sheets of paper (Patent Document 2). In these methods, the RFID can be held therein enough strongly due to the stiffness of the paper if the paper is thick enough or the RFID tag is thin enough.
Also known is a thread comprising a strip-shaped first sheet substrate on which an IC chip allowing at least contactless retrieval of information is mounted and a strip-shaped second sheet substrate laminated on the first sheet substrate, characterized in that holes are bored from the top to the bottom outside the IC chip area (Patent Document 3). If a thread of this construction is affixed to securities, banknote or other sheet with an adhesive, the adhesive penetrates into the through holes and thereby causes wedge effect between the thread and the adhesive, making the thread less likely to separate from the sheet.
[Patent Document 1] JP-A-2002-319006
[Patent Document 2] JP-A-2005-350823
[Patent Document 3] JP-A-2005-284389